Apparatus for feeding aggregate



Feb. 20, 1940. s. M CURDY APPARATUS FOR FEEDING AGGREGATE Original Filed Dec. 8, 1937 2 Sheets-Sheet 1 INVENTOR. (STEWART L M-Cunm I ATTORNEY Feb. 20, 1940. s. L. McCURDY 2,191,096

APPARATUS FOR FEEDING AGGREGATE ori inai Filed Dec. 8, 1937 2 Sheets-Sheet 2 ATTORNEY.

Patented Feb. 29, 1940 UNITED STATES APPARATUSFOR. FEEDING AGGREGATE Stewart L. McCurdy, Pittsburgh, Pa.

Application December8, 1937, Serial No. 178,679.

Renewed August 23, 1939 i 8 Claims. (01. 302-53) The invention relates to pneumatic apparatus for. feeding aggregatasuch as concrete, but is applicable for feeding any finely divided material. The invention has forits principal objects,

l the provision of an improved apparatus in which the feed control is automatic. and which does not depend for its efliciency upon the skill of theop- ,erator; the provision of an apparatus in which any tendency to stall in starting is obviated; and l kthe provision of an apparatus which will feed uniformly without clogging or attention on the part of the operator and with a high degree of efficiency as to volume delivered and compressed air. requirements.

1 One of the important features of construction v contributing to the above results, is the provi sion of a false bottom wall orndiaphragm above the delivery outlet mounted for free oscillatory or vibratory, movement, with a separate air supply i ttherebeneath, so that in the operation of the apparatus, and due to varying conditions of air pressure on the two sides of the bottom wall, such wall will vibrate up and down producing. an.

' merge into a uniform flow by theitime the material merges from the outlet conduit. l A second important feature contributing to the efficiency of the apparatus in starting, is the ar- ..rangement of the air supply, so that on opening "the single control valve, the air is supplied to different parts of the apparatus in a sequence which will prevent stalling, the arrangement being such that the compressed air is first supplied tothe 40, outlet conduit, then above the material in the hopper and below the false-bottom or diaphragm. 'I'hissimplifies the duties of the operator and insures theproper application of .air in starting after each charging of the hopper, Certain embodiments of the invention are illustrated in the accompanying drawings, wherein: t

Figure 1 is a vertical section through the apparatus. Fig. 2,is anendelevation partiallyin section. Fig. 3 is a section on the line III-III of l 50 Fig.1. And Figs. 4 and 5arepartial vertical sections showing modifications.

Referring to the drawings, 6 is a container; of

hopperform having a sliding gate 1 past which the aggregate is supplied from time to time by 55, means/not shown and constituting no partofthe present invention, the gate being operated by means. of an air cylinder 8 whose piston rod 9 is connected, to a bracket l0 at the rear end of the gate. The neck ll of the container is flanged as indicated in Fig. 2 with the edges of the gate 6 1 in opposition thereto. The side and rear edges of the gate have welded thereto the angles l2, l2 (Fig. 2) and I3 (Fig. 1) whose horizontal flanges lie beneath and opposethe flanges on the neck, a gasket being interposed between such flanges, so 10 as to make the, gate air tight when air pressure is supplied to the upper end of the container forcing the gate upward. At its front end the gate is made tight by coming against the gasket Supporting guides for thehorizontalflanges I2, I2 are, provided in theform of anglemembers l5, I5 (Fig. 2) mounted on the screw supports l6, l6.

In order to. keep the flange surfaces of the gate clean, a perforated pipe I] is locatedin the angle 13, as indicated in Fig. 1, and has one end connectedto the flexible air supply hose l8. This connection also serves to apply the airpressure required in the container above the aggregate.

The air thus supplied flows along the flange surfaces and blows out the dust and dirt, the flow into the container occurring between the neck flanges and the bottomsurface of the gate at its edges when thegate is forced upward by the air pressure, so, that it no longer contacts with the neck flanges. Thecleaning efiect of the. air is assisted at suitable intervals by admitting some water into the. pipe l8. This is accomplished through the connection I9 (Fig. 1) provided with a valve 20. Airis supplied to the flexible hose l8 from the connection 2| leading to the'T 22 (Fig.

2) to which this supplied. as later described.

Thecontainer, or hopper, is provided at its lower end with'arectangularoutlet 23 located, as

indicatedin Fig. 1, discharging to the conduit fitting 24 which becomes circular in cross section at its outer end whereit is attached to the conduit pipe 25 leading to the point of delivery of the apparatus. Air under pressure is supplied to the fitting 24 from the main supply'pipe 26 (Fig.

2) via the pipe connections 21, 28, 29 and 30, the

latter of which takesintojthe fitting. The containerfi is provided with a false bottom plate or diaphragm 3i hingedat its upper end on the transverse rod 32 whose ends are suitably secured to the side walls of the container. A baffie 5 g 33 welded to the walls of the container closes the space between the upper edge of the plate 3| and i the walls of-thecontainer ithereabove, so that the aggregate in the container is directed downwardly and to the rightoverthe plate 3| to the outlet the entire feeding cycle.

23. A space at is thus provided below the plate 3 l, and this space is supplied with air under pressure from the pipe 35, such pipe being connected to the pipe 28 via the connections 36,31 and 38 outlet slot is thus provided leading from the space 34 to the conduit 24 along the bottom wall thereof, which space is automaticallyincreased a varying amount under operating conditions since the plate is free to oscillate or Vibrate.

The ilow of air from the-supply pipe 26 to all three connections I8, 30, and 35, is controlled by a single valve 31a located in the pipe,2;-"l, such valve being moved to open and closed positions by the handled-"lb. When the valve is moved to open position, air thus supplied by the hose l3 to the casing above the aggregate, to the space 3&- below the false'bottom plate 3| by the pipe 35, and to the conduit 24 by the pipe 30. The air supplied through the pipes 3!] and 35-is essential 5 in order to givejan uninterrupted'feed of material throughthe-conduit. The air pressure above the aggregate presses it downward to theoutlet 255', butwouldpack at this point and in the conduit, unless loosened and urged along by the air supplied tcthe conduit and below the lower edge of the plate-3 l. An aggregate fed under air pressurehas a tendency to move in an uneven manner, so that the 'air pressure in the apparatus rises and falls due to the release of pressure as the mass starts to move andto the building up of pressure when the mass stops momentarily. These conditions causerthe plate 3| to vibrate up and down throughout theoperation' and loosen the material-at the outlet 23 which is the point at which the-material is apt to become stalled Further, when a stoppage occurs at 23, the pressure in the space 34'builds up moving the plate upward and permitting: more air to discharge belcwthe mass'in the outlet, thus automatically giving the necessary force to free the mass by carrying away the bottom layer. The operation thus requires no' special skill or attention on the part of theoperator.

The air supply arrangement also-insures a feed of the aggregate when the apparatus is first started. At such time, the pressure of the material at the outlet 23 is a maximum" tending to prevent the starting of a feed through theconduit. The air connections, as shown, give an application of air through the connection 311 to the conduit before pressure has a-chance to build up above the aggregatey due to the relatively shorter, larger connectionto the conduit,

as compared with those leading to the upper end of the container. With this arrangement, a proper starting is secured by manipulating only the single valve 310; which may be opened full and left in such position through substantially" The space 34 is provided with a clean-out opening normally closed by the cover plate M. I

Fig. 4 illustrates a modificationin which the false bottom or diaphragm comprises a'plate 4| which is not pivoted like the plate 3| .of the Fig.

I 1 construction, but which can vibrate or oscillate due to the flexibility ofthe metal. The plate issecured at itsupper'edge to the wall of the container preferably: by: welding: to the mem- Fig. 5 illustrates a modification in which the container 6a is. longer and of less height than the containers of Figs. Land 4, this type of container being of advantage where the head room is limited. In order to provide for the more ready emptying or a container of this'type, the swinging plate id is provided in order to give a feed of aggregate from the area 46 of the container. Thisplate is secured at one edge to a transverse shaft 4'] mounted for rotation in bearings in the side walls of the container and provided at one end, exterior of the casing, with a crank arm 48. This crank arm is swung from the hydraulic cylinder t3 provided with a plunger whose piston rod Bil is connected to the crank as shown. As thecontainer empties, the plate 45 is swung upward toward the dotted line position A to cause the aggregateinthe area 46' tofeed to the right onto the plate 5t, which is hinged to the shaft 4? and free to vibrate or oscillate in the same manner as thepl'ate 3 lof the Fig. 1 construction.

Air under pressure is supplied to the apparatus as in the Fig. 1- construction, the air supplied to the space 52- beneath the plates 45 and El fromthe pipe 52a assistingin moving the plate 45, as

the container is emptied.

. to the space above the false bottom plate is dispensed' with. Under these conditions, theweight of the material" causes it to feed downward to the outlet 23 by gravity, and a sufficient air pres"- sure accumulates above: the mass of material, due to the filtration upward therethrough of a' part of the air supplied through the air supply pipe leading to the space beneath the false bottom plate"- and through the pipe 30.

What I claim 1. In combination in a pneumatic conveyor, a' casing having aninlet for'rnaterial at its top and an outlet at its lower side; a conduit leading:

laterally from said outlet, a gate for" said inlet,

an inclinedplat'e constituting a false bottom for the container with its lower edge terminating 1 adjacent the end of the conduit and spaced above the bottom of the container; said plate being mounted'so that said edge is free to oscillate up and down; and means for supplying air under pressure into the container above the inclined plate and into the space below ,su'ch plate. V

2. In'combination in a pneumatic conveyor,- a casing having an inlet, for material at its top and an outlet at its lowerside, a conduit leading air under. pressure for: promoting a: feedtof mate.-

rial. from the: container, one of; which leads into;

an outlet at its lower side, a conduitleading the upper portion of the container, another of which leads into the space below the inclined plate, and the third of which leads into the conduit adjacent said outlet.

3. In combination in apneumatic conveyor, a

casing having an inlet for material at its top and an outlet at its lower side, a conduit leading laterally from said outlet, a gate for said inlet, an inclined plate constituting afalse bottom for the container with its lower edge terminating adjacent the end of the conduit and spaced above the bottom of the container, said plate being hinged at its upper edge so that the lower edge is free to vibrate up anddown and means for supplying air into the container above the inclinedplate and into the space below such plate.

4. In combination in a pneumatic conveyor, a casing having an inlet for material at its top and an outlet at its lower side, a conduit leading laterally from said outlet, agate for said inlet,

5. In combination in a pneumatic conveyor, a

casing having an inlet for material at its top and an outlet at its lower side, a conduit leading laterally from said outlet, a gate for said inlet,

an inclined plate constituting a false bottom for the container with its lower edge terminating adjacent the end of the conduit and spaced above the, bottom of the container, said plate being mounted for free oscillatory movement about its upper edge, an air pressure supply pipe, a control shortest of the three, so that the first application of air, is to the conduit.

6. In combination in a pneumatic conveyor, a casing having an inlet for material at its top and laterally from said outlet, a gate for said inlet, slidably mounted on guideways, an inclined plate constituting a false bottom for the container and with its lower edge terminating adjacent the end of the conduit and spaced above the bottom of the container, said plate being mounted for swinging movement about its upper edge, a connection for supplying air along said guideways to the upper end of the container to clean, such guideways and apply downward pressure to the material in the container, means for supplying water to said connection to promote the cleaning action of the air, and a second connection for supplying air under pressure to the space beneath said plate.

'7. In combination in a pneumatic conveyor, a casing having an inlet for material at its top and an outlet at its lower side, a conduit leading laterally from said outlet, a gate for said inlet, an inclined plate constituting a partial. false bottom for the container with its lower edge ter-, minating adjacent the end of the conduit and spaced above the bottom of the container, said plate being mounted so that it is free to oscillate up and down, a second plate also constituting a partial false bottom pivoted at the upper edge of the first plate and oppositely inclined when the container is. filled withmaterial, power means for swinging the second plate upward about its pivoted edge as the container empties, and means for supplying air into the container above the inclined plates and into the space below such plates.

8. In combination in a pneumatic conveyor,

a casing having an inlet for material at its top and an outlet at its lower side, a conduit leading laterally from said outlet, a gate for said inlet, an inclined plate constituting a false bottom for the container with its lower edge terminating adjacent the end of the conduit and spaced above the bottom of the container, said plate being mounted for free vibratory movement up and down about its edge which is remote from the conduit, and means for supplying air under pressure into the container below said plate and to said conduit adjacent its. inlet.

STEWART L. MCCURDY. 

